First, it appears that you are confusing "database" with table. A Database
is a collection of tables. Each table has rows of data which is organized
in columns.
>From what I understand, you have the following situation:
Table: Parcels
Columns:
dxf (Primary Key, auto_number)
[Description - used for illustration below]
...etc. columns for data about the parcels
Table: Buildings
Columns:
[BuildingID (Primary Key)]
dxf FOREIGN KEY REFERENCES Parcels(dxf)
Address
...etc.
If you have the parcel id (the "dxf") already, you can list all the
buildings on it by simply:
SELECT Address
FROM Buildings
WHERE dxf = <value of dxf>
If you have some other information about the parcel that you want to use as
the identifier:
SELECT P.Description, B.Address
FROM Parcels as P
INNER JOIN Buildings a B
ON P.dxf = B.dxf
WHERE P.Description = '<some description>'
Or similarly, if you have the Address, and you want to show the Parcel
Description:
SELECT P.Description, B.Address
FROM Parcels as P
INNER JOIN Buildings a B
ON P.dxf = B.dxf
WHERE B.Address = '<some address>'
HTH,
Tore.
----- Original Message -----
From: "Diver8" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, February 22, 2003 7:17 PM
Subject: Newbie - How To Link Two Databases
> Hi -
>
> I am new to MySQL & SQL in general. I have been
> reading the documentation at www.mysql.com, but I've
> become quite confused. I hope that one of you can
> clear up a few issues for me.
>
> I have a database called "parcel". The primary key in
> this database is called "dxf", which contains a unique
> number corresponding to each record in the database.
>
> I have a second database called "building". One of
> the columns in this database is called "address". I
> need to be able to pull the data from this column when
> querying the "parcel" database.
>
> The problem I'm having is that while the "building"
> database does contain a column called "dxf", in that
> database "dxf" isn't unique. To clarify, I may have
> multiple rows in the "buildings" database with the
> same entry for "dxf".
>
> To clarify further... the "parcel" database contains
> information regarding land parcels. The "building"
> database contains information regarding buildings on
> these land parcels. "dxf" is the parcel id number.
> While you can only have one parcel of land, you may
> have multiple buildings on that parcel, each with a
> unique address. The parcel information is in the
> first database & the address info is in the second
> database. In the first database, "dxf" is unique (as
> you can only have one land parcel). In the second
> database, "dxf" doesn't necessarily have to be unique
> as you may have multiple buildings on that one land
> parcel.
>
> I hope that made sense.
>
> The problem seems to be that, while each database
> contains a "dxf" entry, there really isn't a unique
> link between the two.
>
> Anyways... when I run a query on the "parcel"
> database, I need to be able to pull any address
> associated with that parcel from the "building"
> database. I can't quite figure out how to do this.
>
> Greatly appreciate any help!
>
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